Search engines don't spare any blogger. E-commerce bloggers must keep in mind the search engines in mind while writing blog posts. SEO friendly writing improves the search of your blog content.
Originality - Focus more on the originality of content and on a consistent basis. It is a habit you will need to cultivate.
Formatting - Your post need not be a circus. If you are not good with formatting, then stick to a theme that is light and descent in colors and the post layout. If you are good with trying new stuff then use that skill to better express through colors, fonts and layouts. Avoid colors that are dark and fonts that are overtly bright.